Cushion underframe

ABSTRACT

Cushion underframe containing a double ended spring with a precompressed compressible material therein adapted for use in a fixed position within the floating sill of a railway car and located substantially centrally of the car for cushioning the forces derived from the couplers at each end.

PAIENI0JuL31 ms sum 2 or 2 FIG. 7

INVENTOR.

BY Q EWM ATTORNEY CUSHION UNDERFRAME In the early cushion underframes in which a floating sill sliding in a fixed center sill extends the length of the car, the floating sill is yieldably resisted in its relative longitudinal movement by long travel coil springs which absorb practically no force, making the underframe dependent for force absorption upon the friction engendered between the floating and fixed sills. Within the limits of its travel, the floating sill of a conventional cushion underframe protects its car from damage mainly by transmitting applied longitudinal forces through the floating sill and considerably reducing the car body as a reactant. It is customary in such underframes to protect the floating sill itself from damage by interposing draft gears or like resilient cushioning units between it and the couplers. However, since the floating sill in which the units are mounted is free to move at all times within the limits of travel of the floating sill and particularly up to the relatively low limit of travel of a coupler in a fixed underframe car, the force capacity of the floating sill is not comparable with that of the draft gear units in a fixed underframe installation when its travel is limited. Consequently, while a car equipped with a cushion underframe is protected, if, in the particular train or string, it is sandwiched between fixed underframe cars with conventional draft gears, substantially the full impact of an applied force, less that amount absorbed by the draft gears, will be transmitted between the adjoining cars through-the floating sill, and the reaction and stresses on the floating sill will be correspondingly high.

In the more recent cushion underframe designs, absorptive capacity has been markedly increased by adding hydraulic cushioning units so that a substantial part of the kinetic energy of the moving floating sill is converted into heat by causing its movements to force a viscose liquid through an orifice. The same principal of force absorption has also been embodied in end-of-car cushioning devices for fixed underframe cars which use hydraulic cushioning units in place of the customary resilient units.

.A hydraulic cushioning unit has a very high energy absorptive capacity and is velocity-sensitive. Since kinetic energy varies as the square of the velocity (WW/2g), it follows that the higher the velocity, the greater the resistance, and, the lower the velocity, the lower the resistance offered by the unit. At extremely low velocities, such as encountered during braking, and run-ins on grades where pressures are low but sustained, the hydraulic unit can be compressed to the limit of its travel with only the return spring force opposing and is, therefore, not effective. An end-of-car hydraulic cushioning device thus leaves much to be desired under such conditions. Too, even though the share of an applied longitudinal force absorbed by a cushion underframe is substantially increased by equipping it with a hydraulic unit, the floating sill is free to move against the resistance of the unit under forces of all levels with the result that the floating sill can still act as a rigid force transmitter and, if limited in its travel by being sandwiched between fixed underframe cars, will transmit substantially the full impact to the backup car less the energy absorbed by the draft gears. Thus, in a coupling operation in which a floating sill cushion underframe car is backed by one having a fixed underframe, the latter will be subjected to a disproportionate share of the applied buffing force, even though the former is equipped with a hydraulic unit.

Accordingly, it is an object of the present invention to provide a cushion underframe in which the longitudinal force from either end of a car is absorbed by a double ended cushioning unit in a manner that eliminates the possibility of eccentric loading of the piston rods.

Another object of the invention is to provide a resilient shock absorber unit which is held in a relatively fixed position within the sliding sill of a railway car cushion underframe by means so constructed to apply concentric loading to both the fixed and sliding sills.

An additional object of the invention is to provide a cushion underframe in which the longitudinal forces are absorbed by a compressible liquid or solid shock absorber unit. I

A further object of the invention is to provide a cushion underframe in which-the shock absorber unit can be readily installed and removed regardless of the amount of precompression.

In order to more fully understand the nature and objects of the present invention, reference should be had to the following detailed description and drawings in which:

PK]. 1 is a plan view partly in cross section, of a preferred embodiment of the cushion underframe of the present invention;

FIG. 2 is a fragmentary side elevation view partly in cross section, taken along lines 22 of FIG. 1; and

FIG. 3 is a front elevation view in cross section, taken along lines 3-3 of FIG. 1.

In accordance with the present invention, there is provided a cushioning unit for railway cars having a longitudinally floating sill within a fixed sill. The unit comprises a double ended spring shock absorber consisting of a sealed cylinder containing a piston within each end and piston rods extending therefrom. A compressible material is disposed within, filling the cylinder between the end caps. Means are disposed at the ends of each piston rod for maintaining the rods in alignment against side loading and to hold the spring in a fixed position within the floating sill.

Referring now to the drawings, there is shown a floating sill member 2 which is mounted for longitudinal sliding in a fixed center sill 4 of a railway car (not shown). Depending upon the application, the floating sill member may be a floating sill extending the length of the car or one of a pair of relatively short sill members slidably mounted in opposite ends of the fixed sill. Mounting one or both of the couplers (not shown) according to whether it is a sill or one of a pair of sill members, the floating sill member mounts for each coupler a conventional cushioning unit (not shown) such as a spring friction draft gear or rubber unit.

Toward the center of the car underframe, a draft lug or backstop 6 is secured as by welding within and to the floating sill 2 on each side of the center line of the underframe. Thus, when the floating sill is set in motion by a longitudinal force, the draft lugs move along with it in a unison.

Also disposed on each side of the center line of the underframe are a pair of spaced key means 8, 10, 12 and 14. The spaced key means are illustrated as being straight bars that pass through both the floating sill 2 and the fixed sill 4 in the proper spaced relationship. The keys are secured to the fixed sill as by welding and the like. To facilitate freedom of movement of the sliding sill relative to the keys, elongated slots l6, 18, 20 and 22 are provided therein. The sliding sill can be a rolled or fabricated section and is usually a single thickness of metal. However, in the area of the elongated slot, an extra thickness of metal 24 and 26 is provided as a reinforcement. Also, where the key bars pass through the fixed sill, reinforcing bars 28 and 30 are provided. The key means are spaced at such a distance to permit passage therebetween of the draft lugs when the sliding sill is in motion.

Disposed substantially centrally of the railway car within the confines of the floating sill is a double ended spring shock absorber. The spring shock absorber consists of a cylindrical or tubular member 34 having a substantially uniform diameter. However, the diameter of the cylinder could vary at each end, depending upon the load requirements. The spring contains a piston 36 and 38 within each end and each piston is provided with a piston rod 40 and 42 which extends through an end of the cylindrical member. The ends of the cylinder are sealed by closure plugs that are secured to the inner surface of the cylinder by mating threads, welding, swaging or the like. Between the end closure plugs within the cylinder is a compressible material 44, either liquid or solid, such as oil, alcohol, hard silicone, etc., but preferably a silicone liquid for this application. The compressible material is precompressed between the end closure plugs by compressing it elastically when it is introduced into the cylinder. The outer ends 46 and 47 of the piston rods are formed or provided with a hemispherically convexed seat 48 and 49 for contact with the followers 50 and 51 which have matching hemispherically concaved seats 52 and 53 to permit equalization or alignment and so prevent lateral loading of the piston rods. Other known equalization means could be utilized to perform this function. More exact details of a suitable double ended spring for use in this construction is disclosed and claimed in copending application Ser. No. l25,669 filed Mar. 18, I971, assigned to the assignee of the present invention and incorporated herein by reference. The follower need not be physically secured to the head. It is disposed within the floating sill adjacent the key means and is of such design that it will not pass between the key means. In the present construction, the follower is merely a rectangular block of metal that is in contact with both the head and the outer edge of the key means. Thus, the double ended spring is held in place by the close bearing relationship of the three parts between the key means without any attachment whatsoever to the sliding sill. The key means, while it is shown on the drawing to be spaced parallel bars, may be of any construction that is attachable to the fixed sill without impeding the movement of the sliding sill and which permits movement of the draft lugs while restricting the piston rod follower against which the sliding sill movement is directed.

A bottom plate 54 is secured as by welding to the lower part of the fixed and moveable sill to completely enclose the cushioning unit.

In operation, when a force is applied against a coupler at the end of the car, the sliding sill moves longitudinally, urging the draft lugs between the key means and against the follower, thus forcing the piston into the cylinder thereby compressing the material therewithin. The removal of the longitudinal force will enable the compressible material to expand to its volume, thrusting the piston outwardly and forcing the draft lugs and sliding sill into the normal or neutral position.

The double ended piston arrangement permits substantially perfect alignment of the unit so that the pistons will not be subjected to side loading. It also enables the capacity to be selectively designed by varying the orifice or valving in each of the two piston heads.

While the invention has been described in connection with preferred embodiments, it should be understood that certain changes or modifications may be made therein without departing from the scope of the present invention.

Having thus described the invention in detail and with sufficient particularity as to enable those skilled in the art to practice it, what is desired to have protected by Letters Patent is set forth in the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a railway car having a fixed center sill, a cushion underframe comprising a floating sill member longitudinally movable in the fixed sill, a double ended spring shock absorber disposed withi n the movable sill, said shock absorber consisting of a sealed cylinder containing a piston within each end retained by end closure plugs and piston rods extending therefrom in the longitudinal direction of the sill, a compressible material disposed within and filling the cylinder between the end closure plugs, spaced key means passing through opposite walls of the fixed and movable sill on each end of the psring shock absorber adjacent the piston rods, follower means disposed within the floating sill and in contact with the piston rods and spaced key means for detachably maintaining the spring in a substantially fixed position within the floating sill and to prevent eccentric loading of the piston rods and draft lugs attached to the floating sill for passing through the key means and engaging the follower means, in contact with the piston rods, in response to longitudinal travel thereof.

2. The railway car of claim ll, in which the piston rods terminate in a hemispherically convexed seat.

3. The railway car of claim 2, in which the follower means contain a hemispherical depression which mates with a portion of the hemispherical seat on the piston rod head.

4. The railway car of claim 1, in which the floating sill contains elongated longitudinal slots in opposed sidewalls through which the key means pass.

5. The railway car of claim 1, in which the key means is removeably secured to oposed walls of the fixed sill.

6. The railway car of claim 1, in which the double ended spring shock absorber is disposed centrally between the ends thereof. 

1. In a railway car having a fixed center sill, a cushion underframe comprising a floating sill member longitudinally movable in the fixed sill, a double ended spring shock absorber disposed withi n the movable sill, said shock absorber consisting of a sealed cylinder containing a piston within each end retained by end closure plugs and piston rods extending therefrom in the longitudinal direction of the sill, a compressible material disposed within and filling the cylinder between the end closure plugs, spaced key means passing through opposite walls of the fixed and movable sill on each end of the psring shock absorber adjacent the piston rods, follower means disposed within the floating sill and in contact with the piston rods and spaced key means for detachably maintaining the spring in a substantially fixed position within the floating sill and to prevent eccentric loading of the piston rods and draft lugs attached to the floating sill for passing through the key means and engaging the follower means, in contact with the piston rods, in response to longitudinal travel thereof.
 2. The railway car of claim 1, in which the piston rods terminate in a hemispherically convexed seat.
 3. The railway car of claim 2, in which the follower means contain a hemispherical depression which mates with a portion of the hemispherical seat on the piston rod head.
 4. The railway car of claim 1, in which the floating sill contains elongated longitudinal slots in opposed sidewalls through which the key means pass.
 5. The railway car of claim 1, in which the key means is removeably secured to oposed walls of the fixed sill.
 6. The railway car of claim 1, in which the double ended spring shock absorber is disposed centrally between the ends thereof. 